Contact terminal



m 9 R. J. KINKAID CONTACT TERMINAL 3 Sheets-Sheet 1 Filed Nov. 27, 1964 Jan. 17, 1967 R. J. KI NKAID 3,299,396

CONTACT TERMINAL Filed Nov. 27, 1964 3 Sheets-5heet 2 Jan. 17, 1967 R. J. KI NKAID 3,299,396

CONTACT TERMINAL Filed Nov. 2'7, 1964' 3 Sheets-Sheet 5 mxwia United States Patent 3,299,396 CONTACT TERMlNAL Robert J. Kinkaid, New Cumberland, Pa., assignor t0 AMP Incorporated, Harrisburg, Pa. Filed Nov. 27, 1964, Ser. No. 414,326 1 Claim. (Cl. 339258) This invention relates to edge connectors for printed circuit boards or similar devices and to contact terminals for such connectors.

An object of the invention is to provide an improved bellows-type contact terminal for printed circuit edge connectors. A further object is to provide a bellows-type contact terminal requiring a minimum amount of material for manufacture. A further object is to provide a bellows-type contact terminal which is resistant to damage resulting from careless or abusive handling. A still further object is to provide a bellows-type contact terminal having improved spring characteristics.

These and other objects of the invention are achieved in a preferred embodiment thereof comprising a stamped and formed bellows-type terminal having a substantially Z-shaped profile. The ends of the intermediate obliquely extending arm in this Z-shaped profile are integral with the substantially parallel arms. One of these parallel arms is provided with means for attachment to an electrical connector while the other parallel arm functions as a contact member engageable with a conductor on the printed circuit board or card in a manner such that the terminal is resiliently compressed to urge the contact arm against a conductor on the board. At least one of the parallel arms is connected to the intermediate obliquely extending arm by means of a bight extending laterally from adjacent side edge portions of the one parallel arm and the intermediate arm. This one parallel arm is thus in folded-over relationship with respect to the intermediate arm and is obtained from stock metal which originally was disposed beside the intermediate arm. In other words, at least one of the parallel arms is obtained by blanking or punching an outline of the arm in the blank of the terminal which is beside the blank which ultimately becomes the intermediate arm. A salient advantage of this method of connecting the one parallel arm to the intermediate arm is that the width of the strip material used in manufacturing terminals in accordance with the invention is substantially reduced so that the total amount of material required for a given number of contacts is reduced. The invention also results in a contact terminal which is resistant to damage as a result of careless or abusive handling and which exerts a closely controlled contact pressure on the printed circuit board during usage.

In the drawing:

FIGURE 1 is a perspective view of a preferred form of contact terminal in accordance with the invention.

FIGURE 2 is a side view with parts broken away of the FIGURE 5 is a sectional side view of an insulating I block adapted to accept contact terminals in accordance with the invention.

FIGURE 6 is a perspective view of a typical edge connector of the type with which terminals in accordance with the invention are used.

FIGURE 7 is a sectional side view of an alternative embodiment of the invention.

A preferred form of contact terminal 2 in accordance with the invention is manufactured in side-by-side strip form with each terminal being integral with a continuous Patented Jan. 17, 1967 carrier strip 4 having spaced apart pilot holes 6. At the time of crimping the individual terminals on the wire ends, the strip is fed to the crimping zone of a suitable press and the leading terminal is crimped onto the end of a wire and severed from the carrier strip.

The terminal 2 comprises a longitudinally extending web 8 having a first pair of said walls 10 extending therefrom by means of which the terminal is crimped onto the conducting core of a wire. A second pair of sidewalls 12 are provided rearwardly of the side-walls 10 for crimping the terminal onto the insulation of the wire 14. The forward section of the terminal comprises a bellows-type spring having a generally Z-shaped cross section or profile and comprising a pair of parallel arms 17, 28 which are connected by means of an obliquely extending intermediate arm 20. The arm 17 projects forwardly from, and is integral with, the web 8 and has a lance 16 struck therefrom which functions to retain the terminal in the connector block.

Arm 17 is connected to intermediate arm 20 by means of a bight 18 formed by bending the arm 20 rearwardly into over-lying relationship with respect to the arm 17 during manufacture. The arm 20 is downwardly concave for a portion of its length and extends substantially parallel to the arm 17 at its rearward or upper end as shown in 22. A right angle flange 24 extends downwardly from the end of the fiat section 22 of arm 20 and is received between sidewalls 40, 42 extending from the web 8 and the lower arm 17. The lower portion (as viewed in FIGURE 2) of flange 24 is bent forwardly of the terminal axis and extends beneath a pair of ears 44 on the sidewalls 40, 42.

The remaining arm 28, which functions as a contact arm, is connected to the fiat section 22 of the arm 20 by means of a laterally extending bight 30 which is integral with adjacent side edge portions of the arm 28 and the portion 22 of the arm 20. It will be noted that the rearward end of the arm 28 is disposed against the upper surface of the fiat section 22 of the arm 20 as indicated in 31 and that the arm 28 is spaced from and parallel to upper surface of the flat section 22 immediately forward of the section 31. This structure is achieved by compressing or closing the bight 30 at its rearward end and functions to control the resilient characteristics of the two arms 28, 20 to achieve optimum results. An additional advantage achieved by compressing the portion 31 of the bight 30 is that the possibility of the printed circuit board being scratched or otherwise damaged by the edge of the arm 28 is avoided.

The arm 28 is provided with a downwardly concave transversely extending rib intermediate its ends as shown at 34, the function of this rib being to cause the forward section of the arm 28 to flex downwardly independently of the rearward section when the printed circuit board is inserted into the connector. The forward end of the arm 28 is bent downwardly towards the arm 17 as shown at 36 so that the end of the arm is located behind the leading edge 41 of the sidewall 40.

While the spaced-apart arms 17, 28 have been described as extending substantially parallel to each other, it will be apparent in FIGURE 2 that, in fact, their .surfaces are slightly convergent when the contact is in its relaxed condition. It is thus not intended to imply that perfect parallelism of these arms 17, 28 is desirable or necessary when the arms are in their relaxed position as shown in FIGURE 2. It should be added that after insertion of th; board, the arms will be substantially parallel to each ot er.

The previously identified sidewalls 40, 42 extend forwardly from intermediate transitional sidewalls 38 on each side of the web 8. The sidewall 42 advantageously projects slightly beyond the leading ends of the arms 3 17, 20, 28, as shown at 41, while the sidewall 40 of the disclosed embodiment ends short of the ends of these arms. An upwardly extending ear 48 is provided on the sidewall 42 intermediate the ends thereof and functions as a stop for preventing forward movement of the terminal through the connector block cavity beyond a desired position as will become apparent from the description below of the block member.

The intermediate arm 20 is advantageously formed with a resilient tendency to spring upwardly a slight distance beyond its position as shown in FIGURE 2 and is prevented from such upward movement by the inwardly directed ears 44, 46 of the sidewalls 4t), 42. This intermediate arm 20' thus constitutes a pre-loaded spring arm which can be flexed downwardly from the position of FIGURE 2 but which cannot move upwardly beyond this position. The ears 44, 46 thus function to precisely determine the overall height of the terminal and to prevent damage to the spring arms 20, 28 which would otherwise occur if the arm 20 were carelessly bent upwardly about the bight 18 as a pivot.

FIGURE 4 shows the blank from which the terminal of FIGURE 1 is produced with the portions of the blank being identified with the same reference numerals (differentiated by prime marks) as are used in FIGURE 13. It will thus be apparent that the bight 18 is formed by bending the forwardly extending tongue member 20' rearwardly over the portions 17, 16 of the blank. The contact arm 28 is formed by bending the arm 28' into overlying relationship with the intermediate arm 20 about the portion 30 of the blank. A distinct advantage of the invention is thus that the stock material of the contact arm 28 is obtained from stock material which is beside the portion 20' of the blank so that a relatively narrow strip of metal can be used in manufacturing terminals in accordance with the invention even though the overall result of a three-arm bellows arrangement is achieved.

The edge connector block 50 which may be of a suitable phenolic or other firm resin material is provided on one side 54 with a transversely extending trough 52 into which the printed circuit board is inserted. Cavities 58, 60 extend through the block 50 from the side 56 and communicate at their forward ends with the trough 52 on opposite sides thereof. These cavities are substantially identical to each other and are each adapted to receive an individual contact terminal 2 so that contact can be made with conductors of either or both sides of the printed circuit board. The cavities are thus of substantially rectangular cross section and are provided with inwardly extending bosses 66 on the sides of the trough 52. One of the rearwardly facing shoulders 67 of one of these bosses 66 is engaged by the leading edge of the ear 48 to prevent movement of the contact terminal through its cavity beyond the position shown. Bosses 66 also function to stabilize the contacts in that the upper edges of the sidewalls 40, 42 bear against the .sides 65 of the bosses when the contacts are in position in the block. A recess 62 is provided on the side of each cavity opposite to the side which communicates with the trough 52, these recesses forming a forwardly facing shoulder 63 for cooperation with the struck-out lances 16 of the contacts to prevent withdrawal with individual terminals from their respective cavities. The terminals are thus assembled to the block 50 by merely inserting them through the cavities 58, 60 from the side 56 until the lances engage the shoulders 63 and the ears engage the shoulders 67.

The surface of the arm 28 of each individual terminal will normally extend parallel to and will be disposed beyond the corresponding side of the trough 52. When the printed circuit board is inserted into the trough 52, the double action spring made up of the arms 28, 20 is resiliently compressed so that the surface of the arm 28 is resiliently urged against the conductor of the board. The forces which press the surface of the arm 28 against the surface of the board are developed by the inherent resilience of the arm 28 and by the resilience of the arm 20 relative to the bight 18. Specifically, the forward portion 35 of the arm 28 is resiliently urged against the surface of the board by virtue of its flexibility in a direction extending normally of its plane about the concavity 34. The portion of the arm 28 which lies between the concavity 34 and the bight 30' is urged against the surface of the board by virtue of the spring effect of the obliquely extending intermediate arm 20 which is flexed downwardly slightly or towards the arm 17 when the board is inserted,

The disclosed embodiment of the invention results in a bellows-type contact having relatively a controlled spring rate over the entire range of its deflection when the printed circuit board is inserted. It will be noted that the arm 28 is flexed in a direction extending normally of its own plane and the arm 20 is similarly flexed normally of its plane. The arms 20 and 28 can thus be thought of as being cantilever beams with beam 28 extending from the free end of the beam 20. These beams are oriented such that they have a low moment of inertia about the neutral surface of flexture. They are not, therefore, inherently stiff but are capable of undergoing substantial deflection at a constant load-deflection rate. Moreover, the resilient behavior of the contact arm 28 is isolated from the behavior of the arm 20 so that the behavior of these arms can be individually controlled.

Some further advantages of the embodiment of FIG- URE 1 are that there is little possibility of damage resulting from abusive or careless handling. The end 36 of the contact arm 28 is protected by the end portion 45 of the sidewall 44. A further protective feature of the invention is that the arm 20 cannot be bent upwardly from the portion of FIGURE 2 since the ears 44, 46 prevent such upward movement of the arm as previously explained.

FIGURE 7 shows an embodiment of the invention in which the intermediate arm is connected to both of the substantially parallel arms by means of laterally extending bights similar to the bight 30. The same reference numerals, difierentiated by the letter a, are used with reference to this embodiment as are used for the embodiment of FIGURE 1. In this embodiment, no sidewall is provided corresponding to the sidewall 40 since the arm 20a is formed from stock material which originally extended parallel to the stock material of the arm 17a. The arm 20a is thus connected to the arm 17a by means of a laternally extending ibight 1811 on adjacent side edge portions of these two arms. The arm 28a is connected to the portion 22a of the arm 20a by means of a bight 300 which is similar to the bight 30 of the embodiment of FIGURE 1.

It should be noted, however, that the bight 30a of the embodiment of FIGURE 7 is on the same side of the terminal as the sidewall 42a rather than on the opposite side as with the embodiment of FIGURE 1. This difference between the two embodiments is dictated by the fact that the arms 20a and 28a are both connected by laterally extending bights 18a, 30a. This embodiment of the invention permits a further reduction in the width of the stock material required to manufacture a three arm-type bellows contact for printed circuit boards.

I claim:

A bellows-type contact terminal having a substantially Z-shaped profile comprising a pair of substantially parallel arms and an obliquely extending arm, one of said parallel arms constituting a contact arm and being connected to said obliquely extending arm by means of a first bight integral with the side edges of said one parallel arm and said obliquely extending arm, the other one of said parallel arms being connected to said obliquely extending arm by a second bight integral with the adjacent ends of said obliquely extending arm and said other parallel arm,

sidewalls integral with said other arm and extending towards said one arm, said one arm having an end portion directed towards said other arm and extending beyond the edge of at least one of said sidewalls, each of said sidewalls having an inwardly directed car, a flange extending from said obliquely extending arm towards said other arm, said flange having portions thereof extending between said other arm and said ears thereby to prevent bending of said obliquely extending arm about said second bight beyond the limits of said ears, and means on the free end of said other arm for securing said terminal to a conductor.

References Cited by the Examiner UNITED STATES PATENTS EDWARD C. ALLEN, Primary Examiner.

10 P. TEITELBAUM, Assistant Examiner. 

